In my first article (Crown Jewels -1/98), I described the General Electric dry process porcelain factory in Schenectady, New York and the earliest pin type attributable to General Electric, the unmarked U-701. In this article I will attempt to detail all of the known installations where the unmarked dry process U-744 have been found and/or documented. I will conclude this series of articles on General Electric with the history of the unmarked U-935A in the near future. In addition to the U-701, the unmarked U-744 and U-935A are the only other early (1895-1897) dry process pin-type porcelain insulators that were thought to have been manufactured by General Electric. From the dates of various installations it appears that the U-701 was the earliest of General Electric's dry process pin types followed by the U-744 and then the U-935A. It appears that General Electric ceased manufacture of dry process porcelain pin types in Schenectady in late 1896-early 1897.

Front view of two U-744's.

Top view of two U-744 's. Note obvious mold line on left 
specimen and obvious dry process bracing on right specimen.

Bottom view of two U-744's. Note porous, granular
dry process porcelain on broken inner skirt on 
the insulator to the right.

The U-744 has only been found unmarked, and consists of a white dry process body with triple petticoats. Usually a highly visible mold line over the crown is present as well as one along the outer edge of the skirt as a result of forming in a 3 piece mold. A single ear is located on each side of the crown to secure the tie-wire instead of a wire groove. On many specimens the ears are often chipped or broken as would be expected with such a fragile design. Some specimens have numerous, fine, black cracks that are typical of an old dry process porcelain. The clear glaze over the white porcelain varies from a thin glaze with a rough texture to a glassy smooth finish. The inner skirt was used as the firing rest and the glaze was wiped off with a cloth before final firing of the insulator. The porosity and granular structure of this early dry process porcelain insulator can be seen quite clearly in the photograph of the bottom of a U-744 with the inner petticoat broken out. 

Although this insulator is the most common of the three classic dry process General Electric's, it is the most difficult to find documentation of its use. Rumors often heard regarding supposed sources of the U-744 including trolley lines in Connecticut, the Pomona line, as well as various lines in Colorado and California. Based upon the evidence I can find, most of these sources appear to be only partially based upon fact and many may be just pure speculation.

The information that is available on the U-744 includes several early photographs. A photo of the U-744 alongside a U-935B (Imperial) is included in a book by Maurice Oudin entitled Polyphase Apparatus and Systems, dated 1900. This photograph depicts the front and bottom view of both of these insulators and is in a section of the book describing the merits of porcelain over glass insulators. No specific information about the insulator is included nor is any mention made of General Electric. 

Another nice photograph of the U-744 was in an 1895 article describing the Niagara power system in Cassiers Magazine. This photograph as well as the information in the original article was republished in a book entitled Harnessing of Niagara also printed in 1895. The photograph was included in a chapter describing various early power lines throughout the world. The article in Cassiers refers to the photograph of the U-744 as a double petticoated porcelain insulator, and is included in a discussion of the state-of-the-art of power line construction in 1895. Further description states that bare conductors should be supported on "heavy double petticoated porcelain insulators as shown on this page (the U-744 photo) mounted on wooden crossarms". The article continues stating that these insulators have withstood a pressure of 90kv without puncture and that "these insulators are sometimes made in two parts, separated by oil" as well as "It is very difficult to keep the oil perfectly clean and the best practice today is to use air separation, which under conditions of service is probably more reliable than separation of oil". This description of the use of oil with the U-744 is very interesting as oil-type insulators were also described for the earlier Taftsville Connecticut power line where the U-701 was found (see CJ Jan. 1998). It is probable that by 1895 the use of oil was found only to be good in theory and impractical in the field. Nothing resembling the second oil holding section of these insulators that is described in Cassiers has ever been found.

The best available information on the use of the U-744 comes from the article High-Voltage Power Transmission, by Chas. F. Scott that was run in the June 30, 1898, journal of the American Institute of Electrical Engineers. This article describes the testing of various pieces of equipment including insulators on an experimental alternating current line at Telluride, Colorado in the period from 1895-1896. This information was first reported in Crown Jewels in Jack Tod's column by Matt Grayson in September 1978. The Telluride test facility included a 2.25 mile line that ran from Ames, Colorado to the Gold King stamp mill. This article includes clear photographs of the test line where three insulator styles were tested. The three styles included the CD244, CD287 and the U-744. The photograph, including measured dimensions of the U-744 is so clear you can see the mold line over the crown. The U-744 is described as a double petticoat insulator that was initially strung with No.6 Band S gauge galvanized iron wire and was later re-strung with No.6 B & S copper wire with a diameter of 0.162". Tests on this line started in December 1895 and initially the line was run between 25kv -33kv for a period of several days. In January, 1896, the line was energized at 45kv and run for a week, and beginning in March, 1896, was run for 37 days at 50kv. These test periods included periods of severe wind, rain, dust and snow. One of the photographs depicts a close up of the pole and snow can be seen on top of the insulators. Evidently there were few problems associated with any of these insulators in these tests. 

At the time of this test (1895-1896) the only companies manufacturing high voltage insulators were Thomas (U-923C for Fred Locke up until October 1895), Imperial (producing the wet-process U-923A for Fred Locke in late 1895) and General Electric for their own transmission projects. Pass & Seymour had produced small (telegraph size), cast, wet process insulators up until the 1895-1896 period before they are thought to have ceased manufacture of pin types as a result of the high cost of their product. The U - 7 44 does not have any characteristics that indicate anyone but General Electric produced them.

50,000 Volts on Large Glass Insulators (Upper Cross-arm) and 
on Porcelain Insulators (Lower Cross-arm.) 
(Photo from AlEE, June 30, 1898.) 
U-744 insulators on bottom two cross-arms in the photo.

Insulators used on High-Tension Tests at Telluride. 
(Photo from AlEE. June 30, 1898.) 
U-744 is insulator on far right.

At no point in the June 30, 1898, AlEE article on the Telluride test line is General Electric mentioned or the manufacturers of any of the insulators described. However, close inspection of this insulator reveals very similar design and manufacturing characteristics to the no name U-701 as well as the U-935A, insulators that have been attributed to GE with near certainty. It also appears that the experimenters in this test took insulators that were in use on various existing transmission lines at that time to conduct an objective comparison of the best available power insulators. It is probable that the Fred Locke U-923 series manufactured by Thomas and Imperial were in such short supply and/or so new to the industry that they were not available for testing and did not have a track record like the U-744.

A second installation where the U-744 was used was on the Big Cottonwood line near Salt Lake City, Utah. Barrie Rufi has spent a lot of time searching the Big Cottonwood Canyon area as well as the power plant itself. Last year Barrie removed a U-744 still mounted on a pin from the Big Cottonwood Canyon power house. It is possible that the U-744 Barrie removed was the last one in service, a full 101 years after it was installed! Barrie informed me that he also found numerous broken U-744's around the station and along the line. As you can see from the photograph Barrie took of the U-744 before he removed it, a broken brown unipart, probably an Imperial U-746 was mounted next to it. The only other pin types Barrie recalled seeing on this line were a small, brown, two piece multipart.

Photograph depicting U-744 mounted on the
 Big Cottonwood Power Plant that Barrie Rufi Removed in 1997. 
(Photo courtesy of Barrie Rufi.)

Barrie Rufi holding U-744 on original wood pin.
Insulator came from small crossarm under window
in top right corner of photo.
(Photo courtesy of Barrie Rufi.)

Closeup of the U-744 Barrie Rufi removed from Big Cottonwood Plant.
(Photo courtesy of Barrie Rufi.)

The Big Cottonwood power plant is described in an article in Electrical World & Engineer dated March 30, 1901. This article describes three (3) power transmission plants and distribution systems in the Salt Lake City and Ogden, Utah area that in 1901, were under ownership of Utah Light & Power Company. One of these was the Big Cottonwood hydroelectric plant located 14 miles southeast of Salt Lake City in Big Cottonwood Canyon. The Big Cottonwood plant and transmission line are described as a General Electric installation completed in 1896. According to Fred M. Locke, A Biography (Gish 1994), this line was installed in June of 1896. The plant contained 4 Pelton waterwheels driving three-phase, 500 volt General Electric generators. The 500 volt generators were stepped up by six, 250kw transformers to 10kv before leaving the power house. The transmission line to Salt Lake City consisted of two, three-phase circuits of No.2 wire on porcelain insulators. The insulators on this line were described as "among the first high-tension insulators turned out and were made by the dry process". Evidently the dry process U-744 units on the Big Cottonwood line were prone to puncture, resulting in burning off the pins. In addition, boys routinely shot at the insulators and this was considered the most serious problem on the line. Further description of these insulators states that "Fully one-third of them have had to be replaced" (as of 1901).

It was previously thought that the Electrical World description referred to the no name U-935A being replaced with Imperial U-935A and U-935B insulators. This appears to be true for the Ogden-Salt Lake City line where no name U-935A insulators were used (see CJ Sept. 1994, pg 11-13). Based upon Barrie's observations, it does not appear that any of the U-935A's were found or used on the Big Cottonwood line. Assuming this is true, the article must be describing the U-744 as the dry process insulators that needed to be replaced.

Barrie also provided me with some historical pamphlets and a book that Utah Power & Light Company produced. The pamphlets contain early photographs of the transmission line leaving this plant and the white U-744's are visible on the lines. Barrie also photographed a pole on the line still in service near the plant and it contains three brown "Redlands" style uniparts, appearing to be Imperial U-746's. These must have been some of the replacements for the U-744 dry process units.

It is quite possible that the March 30, 1901 Electrical World & Engineer article was incorrect and should have referred to the Ogden line where unmarked dry process U-935A's were definitely replaced with Imperial U-935A and U-935B insulators. As I have discovered researching these old journal articles, they were not always 100% accurate. 

Elton also describes in his Fred Locke book that Fred Locke had been asked to fill an order for 4,100 porcelain insulators (U-923A) for Mountain Electric Company of Denver in August of 1896. Interestingly, these insulators were ordered for the Big Cottonwood Canyon transmission line. However, none of these have been found on this line that I am aware. of. I suppose it is possible that these insulators were to be used on another power plant and line known as the "Utah plant", which was located at the tailrace of the Big Cottonwood plant. This line, started up in 1897, is known to have used Imperial insulators and this may be what the Fred Locke order was for.

The third installation of the U-744 that can be verified was in the Fresno, California area. Bill Heitkotter, a former lineman and pioneer insulator collector provided some interesting information to me on his discovery of U-744s in this area. According to Bill, U-744s were used on an old San Joaquin Light and Power Company line that ran between Wishon and Fresno, California. He said they were also used on scattered 12kv lines throughout Fresno and Selma. Bill found an old Pacific Gas and Electric (formerly San Joaquin Light and Power Company) dump in Selma that contained numerous broken U-744's as well as several whole insulators. I have not found any journal articles on this area, but I would bet that these lines are directly connected to local General Electric power plants.

As described in my last article on the General Electric porcelain factory, it is evident that General Electric manufactured dry process porcelain pin-type insulators for their early power plants and transmission lines. Other than the test conducted at Telluride (an objective test of transmission line equipment run as part of a Westinghouse project), all of the power plants and transmission lines associated with the U-744 were totally equipped by General Electric. The other companies (Thomas, Imperial) manufacturing porcelain power insulators at this time do not appear to have been possible manufacturers of these insulators. Although we still cannot say with 100% accuracy that General Electric manufactured the U-744, all evidence points to them as the source of this classic piece.

The U-744 as an insulator that is fairly regularly seen on trade lists as well as at shows. Approximately 25-35 of these insulators are thought to be in the hobby, although there may be more. The book value on these is $30-$50, with most selling in the $30 range. Considering the number of specimens available to collectors and the fact that the U-744 was one of the very first porcelain power pieces in use in this country, this seems to be a real bargain.

References:

Cassiers Magazine, 1895. 
Crown Jewels of the Wire, Nov 1978, Sept. 1994 & Jan. 1995 
Value guide for unipart and multipart porcelain insulators. E. Gish, 1995. 
Harnessing of Niagara. 1895.
Polyphase Apparatus and Systems, Maurice Oudin, 1900.
Journal of the American Institute of Electrical Engineers, "High voltage power transmission", C.F. Scott, June 30, 1898.
The Electrical World and Engineer, March 30, 1901. 
Fred M. Locke. A Biography, E. Gish 1994. 
The Power To Make Good Things Happen, J.S. McCormick, 1990. Utah Power & Light Co.
Insulator Research Service 
Bill Heitkotter - Personal communication.
Barrie Rufi - Personal communication.